The present invention relates generally to adaptive connector assemblies, and in particular, to adaptive connector assemblies which are particularly well-suited to medical applications.
A number of medical procedures involve the catheterization of patients for various reasons. One such application is the administration of anesthesia either in advance of, or during a particular medical procedure. Often, anesthesia must be administered continuously, or at regular intervals, to maintain the effects of the anesthesia during an extended medical procedure. Other such applications include various vascular procedures, various intra-uterine procedures, transfusions, etc. The present application is generally directed to a connector assembly for use in connection with such procedures, particularly those requiring catheterization by means of the so-called "through the needle" introduction technique.
This technique generally involves the use of a needle which is capable of being suitably positioned in a patient's body so as to enable an appropriate, generally flexible catheter to be threaded through the needle so that a distal end of the catheter is appropriately lodged in position within the patient's body, and so that a proximal end of the catheter is capable of extending from the patient's body. After appropriate positioning of the catheter, the needle is removed from the patient's body in a manner which allows the distal portions of the catheter to remain in position as required, and which permits the proximal portions of the catheter to freely extend from the patient's body so that subsequent movement of the patient will not cause the distal portions of the catheter to become dislodged from the patient. Anesthetic or other desired medicaments are then capable of being appropriately introduced to the patient by means of the catheter in conventional fashion.
Of course, in order to enable convenient use of the catheter, it is important that the proximal end of the catheter be provided with an appropriate connector assembly which securely engages the proximal end of the catheter, and enables appropriate medical equipment (syringes, infusion devices, etc.) to be selectively connected to the catheter during the medical procedure in progress. Since such connector assemblies would be disruptive of the catheterization procedure in view of their size and shape, it is therefore necessary that such connector assemblies be attachable to the catheter after positioning in the patient's body.
A variety of connector assemblies have been developed to provide this function. Generally, such connectors make use of a hollow cylindrical body having an aperture at one end for receiving the catheter, and a cap at the other end which threadingly engages the cylinder and which also includes a connector for attachment to appropriate medical equipment, as desired. Positioned within the cylinder is a compressible pellet or plug having a centrally disposed aperture which is capable of passing the catheter through the resulting assembly. Upon placement of the catheter within the cylinder and through the plug which it contains, tightening of the cap with respect to the cylinder causes a compression of the plug which is capable of retaining the catheter within the connector assembly so that the open end of the catheter is exposed to the connector, enabling its connection to medical equipment, as appropriate. Examples of such devices may be had with reference to U.S. Pat. Nos. 4,419,094 and 4,187,848, among others.
Although effective in operation, certain difficulties have been encountered in using such connector assemblies. For example, it will be noted that engagement of the catheter by the compressible plug is primarily dependent upon a threaded fitting. This leads to two complications in operation.
First, a threaded fitting is continuously adjustable. This often leads to undertightening or overtightening of the cap with respect to the cylinder. Undertightening can cause the connector assembly to become dislodged from the catheter, necessitating reattachment of the connector assembly to the catheter, often at times during the medical procedure which are at least inconvenient, and quite possibly inappropriate. Overtightening can cause undue compression of the plug, leading to a partial or total occlusion of the catheter, a condition which is clearly unacceptable and which is often not easily detected until the catheter is ultimately called into use.
Second, in tightening the cap with respect to the cylinder, particularly in connection with an overtightening, it is possible for the torsion which develops between the cap and the plug to twist the plug within the cylinder. At times, this can cause twisting of the catheter within the connector assembly. Again, this can lead to an unacceptable partial occlusion. In extreme cases, this can lead to a complete occlusion, or even damage to the catheter. The latter result can necessitate replacement of the catheter, a condition which is clearly undesirable. Although washers have been positioned between the cap and plug to serve as compression bushings in an effort to eleviate such problems, the results achieved have not proved to be entirely satisfactory.
Also to be considered are certain difficulties in attaching such conventional connector assemblies to the catheter. For example, it is often difficult to properly thread the catheter through the various elements which comprise the connector assembly, particularly when offset apertures are provided to achieve secure catheter retention. This problem is amplified as the number of internal components are increase, such as when compression washers are used to ameliorate the problems of torsioning as previously described. It is therefore not uncommon for improperly aligned components of the connector assembly to impede threading of the catheter through the connector assembly, at times leading to damage of the proximal end of the catheter upon attempting its attachment to the connector assembly (kinking, bending, crimping, twisting, etc.).
Another difficulty arises from the need to appropriately locate the proximal end of the catheter within the connector assembly so that sufficient portions of the catheter are available for secure engagement, but so that the open end of the catheter is correctly positioned within the connector assembly in a manner which correctly exposes the opening to the medical equipment which is to be attached to the connector assembly. Thus, proper placement of a catheter within the connector assembly will require sufficient penetration of the catheter into the connector assembly, to assure satisfactory engagement, while avoiding overextension of the open end of the catheter into the connector assembly, which could interfere with the attachment of medical equipment to the connector. Moreover, such positioning must be developed as the cap is rotated with respect to the cylinder for tightening. This requires three discrete operations (catheter placement, cylinder retention, cap rotation) which are often not easily accomplished by hand, the conventional manner of assembling such components.
It has therefore remained to develop a connector assembly which is simple and reliable in use, and which does not exhibit the foregoing disadvantages.